Energy-measuring apparatus



J. J. KRSTANSKY ET AL 2,877,428 ENERGY-MEASURING APPARATUS March 10, 1959 2 Sheets-Sheet 1 Filed Feb. 25, 1954 ills: I

v zzvmvroas LAJ. KRST /vSKY AND BY 6. A. MITCHELL fl/(s.

March 10, 1959 J. J. KRSTANSKY ETAL' ENERGY-MEASURING APPARATUS Filed Feb. 25, 1954 2 Sheets-Sheet 2 Q. A 'INVENTORS. 7 \AJ. lffisrA/vs/n/ mvo BY 6. A. MITCHELL Arf'r.

United States Patent-O ENERGY-MEASURING APPARATUS 1.'C]aim. 01.. 333-22 This invention relates to energy-measuring apparatus, and more particularly to apparatus for measuring electromagnetic wave energy.

An object of the invention is to provide new and improved energy-measuring apparatus.

Another object of the invention is to provide new and improved apparatus for measuring electromagnetic wave energy.

A further object of the invention is to provide apparatus for gradually absorbing electromagnetic wave energy and measuring the energy at a predetermined point in its absorption.

An apparatus illustrating certain features of the invention may include a wave guide and a water tube. The tube extends from the exterior of the guide into the guide at a small angle and along the interior of the guide, which fits closely around the tube, to absorb wave energy transmitted along the wave guide, and a detector is located in the guide at a point therealong intermediate the ends of the guide.

A complete understanding of the invention may be obtained from the following detailed description of an apparatus forming a specific embodiment thereof, when read in conjunction with the appended drawings, in which Fig. 1 is a fragmentary, front elevation of an apparatus forming one embodiment of the invention;

Fig. 2 is an enlarged vertical section taken along line 2-2 of Fig. 1;

Fig. 3 is a bottom in Fig. l, and

Fig. 4 is a vertical section taken along line 4--4 of Fig. 3.

Referring now in detail to the drawings, there is shown therein a split wave guide comprising channels 11 and 12 of aluminum fastened together by cap screws 13. The wave guide has a centrally located wave-guiding passage 17 of rectangular cross-section extending therealong parallel to the longitudinal axis thereof, and has a thick bottom wall through which semi-cylindrical grooves 18 extend from the bottom thereof at the lefthand end thereof, upwardly and curve to a straight line before intersecting the passage 17, toward which the grooves extend at a slight angle. A cylindrical glass tube 21 of the same diameter as the hole formed by the grooves 18 fits closely in the grooves 18 and extends from a point exteriorly of the lefthand end of the grooves through the curved portion of the grooves and straight along the grooves to a point exteriorly of the righthand end of the wave guide 10, there being no gap between the bottom of the passage 17 and the tube 21. Thus, the tube 21 gradually enters the wave-guiding passage 17 in the lefthand portion of the passage 17 until the tube leaves the passage 17 substantially centrally thereof. The angle between the straight portion of the tube and the longitudinal axis of the passage 17 should be such that the tube causes no reflections or echoes of high frequency waves sent from a magnetron or other waveplan view of the apparatus shown .dielectric strength plastic having generating device into the passage 17 at the lefthand end thereof. v

A highdielectric plastic block 27 bolted to the bottom of the guide 10 with a bore 26 in alignment with the ends of the grooves 18 has a counterbore 28 formed therein in which a guru rubber bushing 29 fits, and a brass hose adapter 30 threaded through a cap 31 secured to the block27 compresses the bushing 29 to form a watertight seal withthe tube.21. A block 35 of a high a plug 36 fitting into thepassage 17, a bore 37 and a counterbore 38 receives ,the tube 21, andis boltedto the waveguide 10. A brass hose adapter 39 threaded through a cap' 40 secured to the block 35 compresses a gum rubber bushing 41 to seal the righthand end of the tube 21 to the bushing. A Nichrome resistance wire 42 for use in calibration is connected to the hose adapters 30 and 39 and extends along the bottom of the tube 21.

The block 35 has bores 45 and 46 and tapped counterbores 47 and 48 for receiving threaded bushings 49 and 50 of an air supply hose 51 and an air exhaust hose 52 provided for pressurizing or flushing the wave guide. The channels 11 and 12 have bores 55 to the passage 17 offset laterally from the grooves 18, and sensing elements 57 carried by housings 59 project into the passage 17, the housings being bolted to the channels 11 and 12.

Hoses 61 and 62 connect the adapters 30 and 39 to a well known type vof water system (not shown) through which water is circulated continuously. The water enters the bushing 30 at a known temperature (room temperature) at a known rate of flow and travels through the tube 21 absorbing substantially all the electromagnetic wave energy entering the lefthand end of the passage 17 from a wave generator (not shown) under test, such as, for example, a magnetron. The water is heated by the wave energy at a rate proportional to the output of the wave generator under test and the increase in heat is measured by a well known device (not shown) to measure the capacity of the generator. The sensing elements 59 are located at points at which most of the wave energy has been absorbed so that they do not cause reflections, and are for sampling the wave energy to measure wave form and frequency.

Since the tube 21 fits closely in the grooves tube enters the passage 17 18 as the at a very slight angle, there are no reflections or echoes of the electromagnetic waves, and the water in the tube absorbs all the wave energy. The guide 10, being split, is constructed easily even though it fits very closely around the tube 21.

It is to be understood that the above-described arrangements are simply illustrative of the application of the principles of the invention. Numerous other arrangements may be readily devised by those skilled in the art which will embody the principles of the invention and fall within the spirit and scope thereof.

What is claimed is:

A wave guide, comprising a pair of elongated horizontal channel members having identical straight longitudinal rectangular shaped grooves extending therethrough, means for securing said channel members together so that the grooves in the abutting faces complement each to form a rectangular wave guide passage, said abutting faces having complementary semi-circular grooves formed in the abutting faces, said semi-circular grooves originating in the bottom surface of the channel members and curving abruptly in the direction of the wave guide passage, said semi-circular grooves gradually approaching and terminating in the wave passage, a glass tube closely fitted within and extending beyond said complementary semi-circular grooves, a first high dielectric block secured to the bottom of the channel members and having a,

to seal the glass tube Within 3 bore formed therein to encompass the origin of the glass tube, a rubber bushing fitted over the origin of the glass tube and positioned within said block, a first threaded cap secured to the first bloek,'a first threaded conductive plug screwed in the cap to compress the rubber bushing to sealgthe glass tube within the channel members, a second high dielectric block secured to the end of the channel members and having a bore formed therein to encompass the terrninus of the glass tube, a second rubber bushing fitted over the terminus of the glass tube and positioned within said second block, a second internally threaded cap secured to the second block, asecond threaded conductive plug screwed into the second cap to compress the second rubber bushing the channel members, and

a resistance wire extending through thetube and connected to the conductive plugs.

References Cited in the file of this patent 5 UNITED STATES PATENTS 2,155,650 Gilbert Apr. 25, 1939 2,471,744 Hershberger May 31, 1949 2,560,536 Althouse July 17, 1951 2,560,903 Stiefel July 17, 1951 1 2,613,270 King 1952 Oct. 7,

OTHER REFERENCES Technique of Microwave'Measurements; vol. 11 of Radiation Laboratory 'Series; McGraw-Hill Book Co., 15 Inc., 1947; pp. 199-204. (Copy in Div. 69.) 

